1. Field of Invention
This invention relates to a diagnostic system adapted to measure accurately minute cranial movements in a human subject and to determine whether these movements deviate from a normal cranial movement pattern and thereby facilitate treatment of the patient by cranial manipulation.
2. Status of Prior Art
In a human skull, the eight cranial bones which together form a hollow protective brain case or cranium are the occipital, sphenoid, ethmoid and frontal bones, as well as the paired temporal and parietal bones. Skull articulations are generally serrated sutures. The concern of the present invention is with the movements of articulated cranial bones and the degree to which deviations from a normal pattern of rhythmic movement reflect a pathological condition that lends itself to treatment by osteopathic manipulative therapy.
In this background section, reference will be made to published papers in scientific journals listed at the end of the section, each paper being identified by a number (1 to 22).
The basic principles underlying the practice of osteopathy center around the need to establish the optimal structure and function of the body in order to prevent or alleviate illness. Historically, allopathy seeks to treat illness by eradicating foreign offenders, and this method of treatment often results in merely alleviating the symptoms. The osteopathic approach which deals with how disturbances in the musculoskeletal system affect other bodily parts, is to consider the body's defenses in attempting to overcome illness. Osteopathic treatment is aimed at improving the body's structural components, thereby improving the body's functional capabilities and allowing the body to heal itself.
Until recently, the efficacy of osteopathic treatment was determined largely by subjective analysis of clinical improvement and patient testimony. During the past two decades, various modalities have been employed in order to objectively demonstrate the efficacy of osteopathic manipulative therapy (OMT). Toward this end, instrumentation such as pressure transducers, forced-displacement meters, and electromyography (EMG) have been utilized (See refs. 9, 10, 13, 16, 18 and 20).
The aim of the present invention is to objectively measure, confirm and evaluate cranial mobility by focusing on the movement of the cranial bones, and to correlate subjective perception of cranial movement with kinematically acquired actual movement. Confirmation can be achieved by isolating the cranial bone movement from movements arising from other parts of the body. The objective measurement of cranial mobility is useful in diagnosis in determining cranial bone alterations as a result of pathological conditions. Also, the results of cranio-facial manipulation can be quantified using a system in accordance with the invention.
Craniosacral theory in osteopathy is based on essentially four factors: namely, (a) movement of bone structures, (b) movement of membranous structures, (c) motility of the central nervous system, and (d) movement of fluids, such as cerebrospinal fluid (CSF) (See refs. 5, 9 and 10 for complete review). This theory postulates that a cranial rhythmic impulse exists which is palpable at various locations in the body, with an average rate of 8 to 14 cycles per minute. This impulse does not correspond with other well defined pulses such as respiration and heart beat. The cranial rhythmic impulse can be evaluated with respect to rate, amplitude and quality, with quality defined in terms of the characteristic wave form (See ref. 10).
The concepts underlying cranial theory which tie it in with other forms of osteopathy involve the body as a unity and its ability for autoregulation which maintains homeostasis. It also takes into account the crucial interrelationship between body structure and function. This theory was originally developed from a study of the structure of the cranial sutures. It was postulated that the orientation of the sutures were such that movement about the suture lines was possible (See refs. 9, 10 and 16). Originally it had been believed that movement of the cranial bones was possible in an infant or child, but not in adulthood, for then these sutures had ossified to the point were movement was no longer possible (See refs. 1 and 17).
However, recent studies have demonstrated the relationship between variations in the volume of cerebrospinal fluid (CFC) and changes in intracranial pressure (See refs. 2, 6, 8, 11, 12, 14 and 22). Marmarou, et al. (see ref. 12) demonstrated that many inanimate containers have ideal elastic properties. Such properties include a coefficient of compliance which does not vary with time or is constant for all degrees of expansion of the container. In such an ideal container, pressure varies linearly with volume and the slope of the volume-pressure curve (or compliance) is constant. Pressure and volume in the compartments containing CSF are not linearly related (See ref. 12). These findings led Marmarou, et al. to conclude that various structures within the central nervous system (CNS) alter their structure or function in order to accommodate various challenges to the system. Marmarou, et al. attributed this ability to the brain, ventricles and blood vessels.
Two of the major assumptions upon which Marmarou, et al. and others (See refs. 2, 8, 14 and 22) have based their findings are that the cranium is a fixed structure, unable to alter its shape or capacity to accommodate any changes in the system. Furthermore, the dura mater, likewise, is a firm fibrous structure which similarly cannot adapt to changes in the structures enveloped within it. Studies performed have demonstrated that the administration of a bolus of fluid into the ventricular system causes a temporary increase in pressure which then returns to steady state (See refs. 11 and 12). It is the conclusion of these investigators that the increased volume causes a chain of events in the circulartory/ventricular system of CNS to modify its function and enable the body to overcome the insult and reestablish homeostasis (See refs. 11 and 12).
One group of investigators (See ref. 11) concluded that the individual effects of these processes relating to pressure are difficult to isolate by experimental means, since formation, absorption and elasticity are mutually interactive, and their combined effects upon intracranial pressure are hydrodynamically complex. One study, performed on infants with hydrocephalus, concluded that a much larger amount of fluid is necessary to produce hydrocephalus than in adults due to the opened suture lines at the fontenelles (See ref. 17).
It was further concluded that the mobility of the cranial bones was able to compensate for increase in CSF volume until the volume was such that the system was overwhelmed (See ref. 17). Intracranial monitoring studies have demonstrated that changes in the cerebrospinal fluid pulse waves exist under conditions of hypercapnia and increased intracranial pressure (See ref. 14). Several investigators have recognized that the cerebrospinal fluid pulse wave was similar to the arterial pulse, but the exact origin of the wave has not been determined (See ref. 14). One investigator (see ref. 3) believed that the wave emanates from the choroid plexus. However, another group (See ref. 4) demonstrated that the cerebrospinal fluid pulse wave could be observed in the lumbar spinal canal when the cervical fluid pathway had been obstructed. A more recent study concluded that the cerebrospinal fluid pulse wave is derived from the transmission of an arterial pulse into the cerebral veins, and that the pulsations within the thin-walled veins are transmitted to the CSF (See ref. 14).
A striking feature of these studies is that many of the conclusions are based on the assumption that the structure and function of the cranium and dura mater are limited and constant. If, however, these assumptions were proven to be false, conclusions drawn from them would likewise be in error and an alternative method of compensation by the CNS would be possible.
There have been studies performed which seek to objectively demonstrate the phenomenon of Cranial Rhythmic Impulse. This is the phenomenon which osteopathic physicians trained in cranial therapy are able to palpate. These studies have been approached anatomically (histologically) and physiologically.
Anatomical or histological studies have focused largely on the suture lines. Retzlaff, et al. (See ref. 15) found the existence, within the suture line, fibrous connective tissue, elastic connective tissue, blood vessels, nerves and sensory endings. They further hypothesized that pain may result from compression along these suture lines due to the structures contained within the suture. Further analysis of the cranial bones and suture lines led Retzlaff, et al. to define four articular patterns observed between parietal bones and adjacent cranial bones: (a) plane suture, (b) squamous suture, (c) serrate suture, and (d) denticulate suture. Retzlaff, et al. further suggested that the plane and squamous sutures allow for a sliding and separating movement, while the serrate and denticulate articulations permit a hinge type of movement. The general conclusion of these investigations is that movement of the cranial bones along suture lines is highly probable.
Physiological studies include a series of experiments performed by Frymann (See ref. 7) designed to investigate the motion of the living cranium. Frymann observed a rhythm which was synchronous with respiration and cardiac activity, and another slower wave motion independent of the other two. Other investigators performed experiments on anesthetized squirrel monkeys to measure parietal bone movement (See ref. 16). They found that when the monkey's head was allowed free movement in a stereotaxic apparatus, the pattern of movement was directly related to cardiac and respiratory activity. With limited movement in the stereotaxic apparatus, right parietal bone movement corresponded to respiratory activity, whereas the left parietal bone appeared to move independently. Complete immobilization resulted in independent motions of each parietal bone with resulting independent wave motion. It was further noted that flexion and extension of the monkey's body resulted in an increased amplitude of these waves. It was concluded from this study that this direct correlation of vertebral column movement and parietal bone movement indicates that alterations in cerebrospinal fluid are responsible for bone movement.
Another study correlated mechano-electric patterns acquired using electrodes on various portions of the subject's body with subjective findings of a physician during craniosacral diagnosis and treatment. This study found that a strong correlation existed between the physician's subjective findings and the data acquired from the sensors (See ref. 20).
A more recent study aimed at identifying parietal bone mobility in anesthetized cats demonstrated that rotational and lateral movement of the parietal bones occur in reference to the medial sagittal suture (See ref. 1). In this study, an isotonic monitoring device was attached to the exposed cranium of anesthetized cats. Data was collected during spontaneous movement as well as movement under stress (i.e., increased intracranial pressure) when a compressive force was applied, a bolus of artificial CSF injected, or induction of hypercapnia.
Their results indicated that cranial motion was affected by insults or challenges to the system. Furthermore, restriction of head movement (i.e., by placement in a stereotaxic apparatus) resulted in a decrease in cranial motion as well as a decrease in the amount of compensation by cranial motion to an imposed challenge. These investigators concluded that lateral and rotational mobility of the parietal bones at the sagittal suture contribute to cranial compliance. They further hypothesize that cranial sutures play an important role in cranial compliance, and have the ability to absorb energy.
Various other studies have demonstrated craniosacral pathology in children with diagnosed emotional or behavioral disorders or learning disabilities (See ref. 21). This investigator has also found a positive correlation between complicated obstetrical delivery and restricted craniosacral motion. These studies, in conjunction with documentation of successful therapy of illnesses and disorders such as dyslexia, reactive and endogenous depressions and hyperkinesis (see ref. 9) lend strong support to the craniosacral theory and practice.
Although utilized in various other aspects (e.g., gait analysis), motion analysis using kinematics has not heretofore been considered useful in testing the hypothesis of cranial movement. No studies have heretofore been performed which allow a two or three-dimensional reconstruction of cranial movement in a human subject. This has been due to the technology itself, for the available kinematic systems lacked the sensitivity to detect minute movements at a reasonable working distance.